There are many situations in which it would be desirable to create a channel through a foreign material located in a body of a patient. For example, the following two papers give examples of such procedures: McWilliams et al., “In Situ Stent-Graft Fenestration to Preserve the Left Subclavian Artery” Journal of Endovascular Therapy Vol. 11, No. 2, pp. 170-174; and McWilliams et al. “Retrograde Fenestration of Endoluminal Grafts From Target Vessels: Feasibility, Technique, and Potential Usage.” Journal of Endovascular Therapy: Vol. 10, No. 5, pp. 946-952, the contents of which are incorporated herein by reference in their entirety.
In some cases, a graft composed of foreign material including a substantially tubular supporting structure, for example a stent, needs to be positioned within a vessel of the body of the patient. However, because of the configuration of the vessel, side branches extending from the vessel may be obstructed by the graft. Restoration of flow through these side branches is relatively difficult to perform with a percutaneous needle because of the relatively large forces required. Also, the relatively large forces exerted onto the needle create a risk that the needle will pass through the foreign material suddenly and damage adjacent tissues.
Radiofrequency (RF) perforation is usable to create channels through biological tissues. It is commonly understood, as stated for example in Shimko et al., “Radio frequency perforation of cardiac tissue: modeling, and experimental results”, Med Biol. Eng. Comput. 38 pp. 575-582 (2000), that in this method, the RF energy serves to rapidly increase tissue temperature to the extent that water in the intracellular fluid becomes converted to steam, inducing cell lysis as a result of elevated pressure within the cell. Furthermore, electrical breakdown may occur within the cell, wherein the electric field induced by the alternating current exceeds the threshold dielectric strength of the medium located between the radiofrequency perforator and the cell, causing a dielectric breakdown. In addition, mechanical breakdown may occur, wherein alternating current induces stresses on polar molecules in the cell. Upon the occurrence of cell lysis and rupture; a void is created, allowing the device to advance into the tissue with little resistance. Since foreign materials are not made out entirely, or at all, of cellular-based biological tissue, this mechanism seems unlikely to work in such materials.
Against this background, there exists a need in the industry to provide a novel method for creating a channel through a foreign material. An object of the present invention is therefore to provide a method for creating a channel through a foreign material.